Abstract: The geological conditions of the “three soft” coal seam weaken the bearing capacity of the section coal pillar. In order to avoid the instability of the coal pillar, the large coal pillar is often retained, resulting in waste of resources. In order to improve the recovery rate of coal resources, this paper takes the reasonable width optimization of section coal pillar in 1513 working face of Anyang Coal Mine as the research background. Based on the occurrence characteristics of “three soft” coal seam, the support stress and elastic-plastic zone in coal pillar are studied by theoretical analysis and numerical simulation. The reasonable width of section coal pillar is obtained, and its scientific rationality is verified by field application. The research shows that the stress in the plastic zone of the section coal pillar is significantly higher than that in the elastic core zone, and the two-zone range is obtained. Combined with the numerical simulation of the stress distribution characteristics of different coal pillar widths, the deformation and failure characteristics of the section coal pillar with different widths and the distribution characteristics of the plastic zone are obtained. The research conclusion is applied to on-site monitoring, which show that the reasonable width of section coal pillar in 1513 working face is 20 m. This study improves the recovery rate of coal seam to a certain extent, reduces the waste of coal resources, increases economic benefits, and provides a useful reference for the optimization design of section coal pillar under similar mining conditions.